1. Field of the Invention
The present invention relates to a lighting circuit. More particularly, the present invention relates to a lighting circuit for lighting a vehicular lamp.
2. Description of the Related Art
Conventionally, a switching regulator is known that supplies power to a light source of a vehicular lamp as disclosed in Japanese Patent Application Laid-Open No. 2001-215913, page 3 and FIG. 7, for example. An output voltage of the switching regulator is controlled based on, for example, a current flowing in the light source.
Various light sources such as a high-beam light source and a low-beam light source in a headlamp, are mounted on a vehicle. Therefore, in order to drive these various light sources by using the switching regulator, it is necessary to provide the switching regulator for each light source, thus increasing the cost.